赤水河弯曲河段地貌特征参数统计分析

Statistical Analysis of Geomorphological Parameters in Meandering Sections of Chishui River

探究弯曲河段的地貌演变规律,揭示河流蜿蜒形态发展机理和地貌形态发育过程,可为西南山区河道保护与生态修复提供定量参考。选取赤水河干流自然蜿蜒的125组弯曲河段,应用统计学原理,归纳分析蜿蜒波形波长、蜿蜒河道波形振幅、曲率半径、中心角、半波弯曲弧线长度、横向偏移度、河道转向角、河道平滩宽度及弯曲率共9项指标的参数分布规律,并基于经验关系公式求算赤水河干流地貌特征系数值范围。结果表明,赤水河左右两岸的弯曲发育有较强的对称性,干流弯曲河段的河道类型主要为微弯型,各指标参数的分布规律与赤水河地形地势变化密切相关。赤水河水系发育情况统计的经验公式中,弯曲河段蜿蜒波形波长和河道平滩宽度系数k_(1)主要变化为[13.2,20.4],曲率半径与河道平滩宽度系数k_(2)主要变化为[3.0,5.7],半波弯曲弧线长度与河道平滩宽度系数k_(3)主要变化为[13.8,23.5]。研究表明,经验公式适用于赤水河地貌特征,且推断平原河道与山区河道所对应的系数值范围具有不同的变化规律。

Geomorphological diversity of rivers is the basis of biodiversity and ecosystem integrity of rivers,and geomorphological parameters provide basic information for planning the restoration of river ecosystems.In this study,Chishui River was selected for study because of its natural attributes.The geomorphological characteristics of 125 meandering segments of the river were analyzed,aiming to reveal the mechanisms driving the geomorphological evolution of the meanders.Nine geomorphological parameters of the meandering segments were selected for the analysis of landform distribution using statistical techniques that included the meandering waveform length,amplitude,radius of curvature,central angle,half-wave arc length,lateral deviation,and the channel turning angle,flat beach width and bending rate.The range of characteristic coefficient values of the geomorphological parameters was then calculated based on empirical relationships.Results show that the curve development of Chishui River on the left and right banks is strongly symmetric.The meandering sections of the mainstem tend to be slightly curved,and the distribution of the geomorphological parameters was closely related to the topography of Chishui River.Based on statistics collected on the Chishui River system,various coefficient ranges for the empirical formula were obtained.The change intervals of coefficient k_(1) for meander wavelength and channel flat width of the curved river section were 13.2 and 20.4;the change intervals of coefficient k_(2) for curvature radius and the channel flat width were 3.0 and 5.7;the change intervals of coefficient k_(3) for half-wave bending arc length and river flat width were 13.8 and 23.5.Our results show that the empirical formula is suitable for the landform characteristics of Chishui River,and the coefficient value ranges infer that plain river courses and mountain river courses have different change laws.